title: Evolution of mild cognitive impairment in Parkinson disease.
abstract: OBJECTIVE
  We examined the development of Parkinson disease (PD)-mild cognitive impairment (MCI) in patients with newly diagnosed PD over 5 years using recently proposed consensus criteria, and we assessed the reliability of the criteria.
  
  
  METHODS
  Patients with PD (n = 123) underwent extensive neuropsychological testing at baseline and after 3 (n = 93) and 5 years (n = 59). Two neuropsychologists independently applied the PD-MCI criteria to examine the interrater and intrarater reliability.
  
  
  RESULTS
  At baseline, 35% of patients had PD-MCI. Three years later, 53% of the patients had PD-MCI. At 5-year follow-up, 20 patients who had PD-MCI at an earlier assessment had converted to PD dementia and 50% of the remaining patients without dementia had MCI. The interrater reliability (kappa) was 0.91. The intrarater reliabilities were 0.85 and 0.96.
  
  
  CONCLUSIONS
  Approximately one-third of patients with newly diagnosed PD fulfill the consensus criteria for PD-MCI; after 5 years, this proportion is approximately 50% of patients without dementia. The criteria have good interrater and intrarater reliability.
authors.affiliation: Department of Brain and Cognition, University of Amsterdam, Amsterdam, the Netherlands. M.Broeders@uva.nl
authors.forename: M
authors.initials: M
authors.lastname: Broeders
authors.forename: R M A
authors.initials: RM
authors.lastname: de Bie
authors.forename: D C
authors.initials: DC
authors.lastname: Velseboer
authors.forename: J D
authors.initials: JD
authors.lastname: Speelman
authors.forename: D
authors.initials: D
authors.lastname: Muslimovic
authors.forename: B
authors.initials: B
authors.lastname: Schmand
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000209:etiology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000523:psychology*; D015203:Reproducibility of Results; D012189:Retrospective Studies